This invention relates to methods and apparatus useful in the development of molds used in vacuum forming in a printed thermoformable plastic sheet, an accurate three-dimensional relief reproduction of an original three-dimensional article.
In our co-pending U.S. patent application Ser. No. 08/408,900 filed May 22, 1995 and entitled Vacuum Formed Three-Dimensional Surface Article, we have described:
1) a vacuum forming process for molding a thin sheet of thermoformable plastic to produce an accurate three-dimensional relief reproduction of an original artwork or the like;
2) an apparatus for vacuum forming a thin sheet of thermoformable plastic into an accurate three-dimensional relief reproduction of an original artwork; and
3) methods for producing male molds for use in making female molds which in turn are used in the vacuum forming of thermoformable plastic sheet to form an accurate three-dimensional relief reproduction of an original artwork.
There is a significant consumer demand for faithful inexpensive reproductions of art. In making such reproductions it has been found to be very important to reproduce the texture of the work such as the brush stroke, which may reflect light in a particular manner. As described in our co-pending U.S. application, various methods have been put forth in an attempt to re-create a three-dimensional relief of the original work. Such techniques are described in U.S. Pat. Nos. 4,285,744; 4,971,743 and French Patents 1493516 and 1548337. There are however problems associated with the techniques described in those patents and attempts to overcome those problems have been described in Canadian patent application 2,020,206; U.S. Pat. Nos. 4,001,062; 5,182,063 and 5,201,548. The activities continue in respect to overcoming various problems with the prior art processes, such as described in U.S. Pat. Nos. 4,971,743; 5,116,562 and 4,285,744. The invention defined in our co-pending application using vacuum-forming has overcome many of the problems associated with the prior art techniques and is able to provide a high quality product in a cost-effective manner. An aspect of our prior methods and apparatus involve the production of the male mold for use in making the female mold which in turn is used in the vacuum forming of the thermoformable plastic sheet. Quite unlike normal vacuum forming techniques, applicants have discovered that a very acceptable product can be made from a female mold and still retain the features of the three-dimensional surface definition and registration of that definition with the image on the plastic sheet. Various techniques are described in the aforementioned co-pending U.S. application for making the male mold so as to provide on its surface, a surface relief texture which is essentially the same as the original. A female mold is then made by pouring onto the surface of the male mold a suitable castible material which when hardened and released from the male mold provides a female mold having the artistic creation of the surface texture of the original work reproduced therein. The usual type of castible material has the tendency to shrink as it hardens in producing the final female mold. In particular, if the castible material is of an epoxy resin there is considerable shrinking during the curing process so that the female mold in its cured form is smaller than the original work from which the male mold was made.
It is an object of an aspect of this invention to overcome the problems associated with the castible shrinkable material from which the female mold is made and which greatly enhances the flexibility in making of the female mold and greatly accommodates various changes that one would like to make in producing multiples of the male mold from the which the female molds would be made.
In accordance with an aspect of the invention, a programmable system for dimensionally expanding and printing a picture image on a printable sheet for use in making a picture print thermoforming female mold of castible shrinkable material, comprises:
i) a programmable computer having a memory in which the picture image is digitally stored;
ii) a computer driven printer having a moveable printing head for printing the picture image on a sheet as the printing head moves relative to a sheet;
iii) the computer having a program for dimensionally expanding a picture image stored in the memory, the program expanding a stored picture image from:
a) an original dimensional size having a length and a width identical to a final picture print size on a thermoformable plastic sheet to be molded in such female mold, to:
b) an expanded dimensional size having an expanded length and width equal to an extent to which such female mold of such castible shrinkable material shrinks from its original poured state to its hardened state,
iv) the computer being actuated to drive the printer to print such expanded image onto a sheet.
In accordance with another aspect of the invention, a method for dimensionally expanding and printing a picture image on a printable sheet and making a picture print thermoforming female mold of castible shrinkable material. The method comprises:
i) digitally storing the picture image in a computer memory;
ii) printing the picture image on the sheet by use of a computer driven printer having a moveable printing head which prints the image as the printing head is moved relative to the sheet;
iii) dimensionally expanding the picture image stored in the memory from:
a) an original dimensional size having a length and a width identical to a final picture print size on a thermoformable plastic sheet to be molded in the female mold, to:
b) an expanded dimensional size having an expanded length and width equal to an extent to which the female mold of such castible shrinkable material shrinks from its original poured state to its hardened state,
iv) printing the expanded picture image onto the sheet;
v) brushing onto the printed expanded image a hardenable compound to replicate on the printed image, brush strokes of an original picture image to form a male mold;
vi) making a female mold by pouring the castible shrinkable material on the male mold, curing the castible shrinkable material whereby the material shrinks a predetermined extent in length and width to take on the original dimensional size of the length and width for the final picture print size.
In accordance with another aspect of the invention, a process is provided for producing a male mold which replicates three-dimensional surface relief of an original. The process comprises:
i) printing a picture image of the painting on a printable sheet;
ii) brushing onto the printed picture image a hardenable compound to replicate on the image the three-dimensional aspects of the original;
iii) allowing the compound to harden to produce thereby the male mold.